The rolling blackouts are still possible especially between 6 a.m. and 9 a.m., but ERCOT officials said the condition of state's power grid is improving despite heavy consumer demand created by the winter storm raking portions the state.

ERCOT, which manages the flow of electric power in much of the state, will be monitoring the grid to determine if the statewide rotating outages need to be instituted again because of unexpected losses of power generation.

Consumers are urged to conserve their power use, particularly during peak demand periods.

ERCOT officials said rotating outages are controlled, temporary interruptions of electrical service. They are initiated by individual utility companies when ERCOT's reserve power supplies are exhausted.

Rotating outages are the last step taken in power emergencies, ERCOT officials said.

In Houston Wednesday, CenterPoint Energy said the rolling outages began about 5:45 a.m. and left some 330,000 customers at a time without power for up to about 45 minutes. Officials tried to avoid cutting power to critical services, such as hospitals.

Traffic signals were out throughout the city and Harris County. Also, Houston Fire Department officials said firefighters were dispatched to 30 elevator rescues, many of which were probably related the rolling power outages, fire officials said. Most of the elevator rescues occurred between 7 a.m. and 10 a.m.

On average, HFD officials said, firefighters respond to an average of 2 to 3 elevator rescues a day.